Systems, apparatuses and methods for a signal extension padding scheme

ABSTRACT

Systems, apparatuses and methods described herein provide a method for padding a signal extension of orthogonal frequency-division multiplexing (OFDM) symbols. A transceiver may obtain a plurality of data symbols for transmission, and determine that a number of information bits for a last symbol of the plurality of data symbols is not an integer value. A special padding rule may be applied to add padding bits to the last symbol. A number of coded bits for the last symbol may be determined when the number of information bits for the last symbol has changed, and the plurality of data symbols for data transmission may be encoded based on the determined number of coded bits for the last symbol.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication entitled “SYSTEMS, APPARATUSES AND METHODS FOR A SIGNALEXTENSION PADDING SCHEME”, having a Ser. No. 16/295,499, having a filingdate of Mar. 7, 2019; which is a continuation application of U.S. patentapplication entitled “SYSTEMS, APPARATUSES AND METHODS FOR A SIGNALEXTENSION PADDING SCHEME”, having a Ser. No. 15/179,150, having a filingdate of Jun. 10, 2016; which claims the benefit of U.S. provisionalapplication entitled “PADDING WITH SIGNAL EXTENSIONS”, having a Ser. No.62/174,158, and having a filling date of Jun. 11, 2015, having commoninventors, and having a common assignee, all of which is incorporated byreference in its entirety.

FIELD OF USE

This disclosure relates to a padding scheme for orthogonalfrequency-division multiplexing (OFDM) signal extensions in a wirelessdata transmission system, for example, but not limited to a wirelesslocal area network (WLAN) implementing the Institute of Electrical andElectronics Engineers (IEEE) 802.11 standard and any other standardsand/or networks that can provide wireless transfer of data in outdoordeployments, outdoor-to-indoor communications, and device-to-device(P2P) networks.

BACKGROUND OF THE DISCLOSURE

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of theinventors hereof, to the extent the work is described in this backgroundsection, as well as aspects of the description that may not otherwisequalify as prior art at the time of filing, are neither expressly norimpliedly admitted to be prior art against the present disclosure.

Orthogonal frequency-division multiplexing (OFDM) is often used toencode data on multiple carrier frequencies to improve data transmissionperformance under undesirable channel conditions. The current IEEE802.11ax standard has adopted a 4×OFDM symbol duration to improve dataefficiency. The longer data symbol, however, can often result in heavierprocessing complexity at the receiver. To help the receiver to processthe longer data symbol with as little processing logic overhead aspossible, a signal extension (SE) of multiples of 4 μs can be used toallow additional processing time at the receiver before the next datasymbols is received. Further discussion of SE with OFDM data symbols canbe found in U.S. application Ser. No. 14/728,802, entitled “HighEfficiency Orthogonal Frequency Division Multiplexing (OFDM) PhysicalLayer (PHY),” filed on Dec. 3, 2015, which is herein expresslyincorporated by reference.

Padding bits can be added to the last OFDM symbol according to the SE.For example, SE can be set to be a×4 μs where a=1, 2, 3 or 4. In thiscase, the useful bits in the last OFDM symbol may be determined based ona×¼ of N_(CBPS), where N_(CBPS) denotes the number of coded bits persymbol. When N_(CBPS) is not multiples of 4, some modulation codingselection (MCS) scheme and SE combinations may lead to setting thenumber of padding bits to a non-integer number that is generallydifficult, if not at all impossible, to implement.

SUMMARY

Systems, apparatuses and methods described herein provide a method forpadding a signal extension of orthogonal frequency-division multiplexing(OFDM) symbols. The method comprises obtaining, at a transceiver, aplurality of data symbols for transmission, and determining that anumber of information bits for a last symbol of the plurality of datasymbols is not an integer value. The method further comprises applying aspecial padding rule to add padding bits to the last symbol. The methodfurther comprises determining a number of coded bits for the last symbolwhen the number of information bits for the last symbol has changed, andencoding the plurality of data symbols for data transmission based onthe determined number of coded bits for the last symbol.

In some implementations, the method further comprises applying a signalextension for the last symbol of the plurality of data symbols. The lastsymbol has a relatively shorter length compared to other symbols fromthe plurality of data symbols. The number of information bits for thelast symbol is divided by a plurality of encoders when the plurality ofencoders are used.

In some implementations, the method further comprises adding a number ofpadding bits to the last symbol before forward error-corrective encodingbased on the number of coded bits for the last symbol.

In some implementations, applying the special padding rule furthercomprises: adding a number of padding bits to the last symbol beforeencoding, wherein the number of padding bits equals the number ofinformation bits for a last symbol; and unevenly distributing the numberof padding bits across a plurality of encoders.

In some implementations, applying the special padding rule furthercomprises: adding a number of padding bits to the last symbol to makethe number of information bits for the last symbol an integral value;and evenly distributing the number of padding bits across a plurality ofencoders.

In some implementations, applying the special padding rule furthercomprises applying dynamic puncturing for a plurality of encoders.

In some implementations, applying the special padding rule furthercomprises enforcing the number of information bits for the last symbolto be an integer value by taking a ceiling or floor operation.

In some implementations, applying the special padding rule furthercomprises adopting a compatible value to be a number of scheduled datasubcarriers such that the number of coded bits for the last symbol andthe number of information bits for the last symbol are both integers.

In some implementations, applying the special padding rule furthercomprises determining an integer value for the number of coded bits forthe last symbol by taking a ceiling or floor operation. The specialpadding rule further comprises determining a signal extension parameterbased on the integer value for the number of coded bits for the lastsymbol, and adding a plurality of padding bits to the last symbol beforeencoding.

In some implementations, determining the number of coded bits for thelast symbol further comprises dividing the changed number of informationbits for the last symbol by a coding rate, and taking a ceilingoperation over a result of the dividing.

Systems, apparatuses and methods described herein further provide asystem for padding a signal extension of OFDM symbols. The systemcomprises an input data processing module to obtain a plurality of datasymbols for transmission. The system further comprises a pre-encodingpadding module communicatively coupled to the input data processingmodule. The pre-encoding padding module is configured to determine thata number of information bits for a last symbol of the plurality of datasymbols is not an integer value. The pre-encoding padding module isfurther configured to apply a special padding rule to add padding bitsto the last symbol. The pre-encoding padding module is furtherconfigured to determine a number of coded bits for the last symbol whenthe number of information bits for the last symbol has changed. Thesystem further comprises an encoding module to encode the plurality ofdata symbols for data transmission based on the determined number ofcoded bits for the last symbol.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the disclosure, its nature and various advantageswill become apparent upon consideration of the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich like reference characters refer to like parts throughout, and inwhich:

FIG. 1 provides an exemplary block diagram illustrating a transceiversystem that includes a data encoder in which a padding scheme isemployed, in accordance with various embodiments of the disclosure.

FIG. 2 provides an exemplary logic flow diagram illustrating a paddingprocedure that is implemented in an encoder (e.g., 101 in FIG. 1 ), inaccordance with various embodiments of the disclosure.

FIG. 3 provides an exemplary logic diagram illustrating an examplespecial padding rule by applying unequal bits per encoder, in accordancewith various embodiments of the disclosure.

FIG. 4 provides an exemplary logic diagram illustrating an alternativeimplementation of an example special padding rule by adding additionalpadding bits, in accordance with various embodiments of the disclosure.

FIG. 5 provides an exemplary logic diagram illustrating an alternativeimplementation of an example special padding rule by apply dynamicpuncturing for each encoder, in accordance with various embodiments ofthe disclosure.

FIG. 6 provides an exemplary logic diagram illustrating an alternativeimplementation of an example special padding rule by enforcing aninteger number of coded bits per symbol for short OFDM symbols, inaccordance with various embodiments of the disclosure.

DETAILED DESCRIPTION

This disclosure describes methods and systems for a padding scheme fororthogonal frequency-division multiplexing (OFDM) signal extensions (SE)in a wireless data transmission system. According to this disclosure, anew padding procedure including special padding rules is adopted whenthe calculated number of data bits per symbol for the last OFDM symbol(N_(DBPS,Last)) is not integer, or the calculated number of data bitsper symbol per encoder

N_(DBPS, Last)/N_(ES)(where N_(ES) denotes the number of encoders) is not an integer whenthere are more than one encoders per regular data symbol. The number ofcoded bits N_(CBPS,Last) for the last symbol may be re-computed based onthe changed N_(DBPS,Last), and these parameters can then be used forencoding.

FIG. 1 provides an exemplary block diagram illustrating a transceiversystem that includes a data encoder in which a padding scheme isemployed, in accordance with various embodiments of the disclosure. Asshown in FIG. 1 , a transceiver system 100 may obtain input data 110 fortransmission, e.g., from a processor of the system. An encoder 101 atthe transceiver 100 may include an input data processing module 102 topre-process data bits before forward error correcting (FEC) encoding.For example, the input data processing module 102 may determineparameters such as the number of coded bits per data symbol, a SEparameter, and/or the like, as further illustrated in 201-203 in FIG. 2.

The encoder 101 may further include a pre-FEC padding module 103, whichmay pad additional bits to the OFDM symbol, and then pass the paddedbits to the FEC encoding module 104. A post-FEC padding module 105 canbe employed to fill up the last OFDM symbol, e.g., with zero-padding.The padded data symbols may then be passed on to the interleaver 120 andmodulation module 130 before transmitting the data 135. The data 135 maybe modulated symbols output by modulation module 130.

FIG. 2 provides an exemplary logic flow diagram illustrating a paddingprocedure that is implemented in an encoder (e.g., 101 in FIG. 1 ), inaccordance with various embodiments of the disclosure. At 201, anencoder may determine the coded bits per symbol. For example, theencoder may determine the coded bits per symbol (N_(CBPS)) for a user ubased on the following determinationN _(CBPS) ^((u)) =N _(SD) ^((u)) ×N _(SS) ^((u)) ×N _(BPSCS) ^((u))where N_(CBPS) ^((u)) denotes the number of coded bits per symbol in a4× symbol for user u; N_(SD) ^((u)) denotes the number of scheduled datasubcarriers in a 4× symbol for user u; N_(SS) ^((u)) denotes the numberof special strings in a 4× symbol for user u; and N_(BPSCS) ^((u))denotes the number of coded bits per subcarrier per spatial streams in a4× symbol for user u, u=0, 1, 2, 3, etc. It is noted that for all theparameters defined above, the values can be configured differently for aspecific user u, and the superscript “u” may be adopted or skippedinterchangeably throughout the disclosure.

Specifically, when single user (SU) or multi-user (MU) multiple-inputmultiple-output (MIMO) system with physical protocol data unit (PPDU) isemployed, N_(SD) denotes the number of available data subcarriers.

At 202, the encoder determines the info bits per regular symbol. Forexample, the encoder may determine the info bits per symbol (N_(DBPS))based on the following N_(DBPS) ^((u))=N_(CBPS) ^((u))×R^((u)), whereN_(DBPS) ^((u)) denotes the number of data bits per symbol in a 4×symbol for user u, and R denotes the coding rate for user u, u=0, 1, 2,3, etc.

The encoder may also determine the number of encoders per regularsymbol, e.g.,

N_(ES)^(u) = ⌈N_(DBPS)^((u))/R^((u))⌉,wherein “┌ ┐” denotes a ceiling operation. For all valid number ofscheduled data subcarriers, N_(DBPS) ^((u)) and

N_(DBPS)^((u))/N_(ES)^((u))are integer numbers.

At 203, the encoder may start a pre-FEC padding procedure by determininga SE parameter “a” for the last OFDM symbol (i.e., a short symbol).Further discussion on determining the SE parameter “a” can be found incommonly owned U.S. application Ser. No. 14/728,802, which is hereinexpressly incorporated by reference. For example, the SE parameter a maytake a value of 1, 2, 3 or 4.

At 204, the encoder may determine the number of information bits for ashort (1×) OFDM symbol. In one example, the number of information bitscan be determined based on the following:

$N_{{DBPS},{short}}^{(u)} = {\frac{1}{4}{N_{DBPS}^{(u)}.}}$For another example, the number of information bits can be determinedbased on the following:

$N_{{DBPS},{short}}^{(u)} = {{N_{{CBPS},{short}}^{(u)} \times R^{(u)}} = {\frac{1}{4}N_{SD}^{(u)} \times N_{SS}^{(u)} \times N_{BPSCS}^{(u)} \times {R^{(u)}.}}}$

At 205, the encoder determines the padding bits for the last OFDMsymbol. For example, the number of data bits of the last symbol can bedetermined as follows: N_(DBPS,last) ^((u))=a·N_(DBPS,short) ^((u)). Thenumber of padding bits can be determined as follows: N_(Pre-FEC-Pad)^((u))=N_(DBPS,last) ^((u))−(N_(inf o) ^((u))−(N_(SYM)−1)·N_(DBPS)^((u))), where N_(inf o) ^((u)) denotes the number of information bitsfor user u, and N_(SYM) denotes the number of symbols.

At decision 206, the encoder may determine whether N_(DBPS,Last) or

N_(DBPS, Last)/N_(ES)is an integer. If one of the two values is not an integer, the encodermay apply special padding rules at 207, which may be further illustratedin various examples in FIGS. 3-6 . After special padding rules have beenapplied at 207, the encoder may calculate the number of coded bits forthe last symbol at 208 (as further discussed in connection with FIG. 6), and use the computed parameters for FEC encoding at 209.

Specifically, at 207, for a non-short padding scenario, e.g., when theSE parameter a=4, the last symbol can be encoded in the same way as aregular long symbol. Or alternatively, when the SE parameter a=1, 2 or3, special padding for a non-integer N_(DBPS,Last) or

N_(DBPS, Last)/N_(ES)are discussed in connection with FIGS. 3-6 .

FIG. 3 provides an exemplary logic flow diagram illustrating an examplespecial padding rule by applying unequal bits per encoder, in accordancewith various embodiments of the disclosure. Continuing from 207 in FIG.2 , the encoder may determine whether N_(DBPS,Last) is an integer at301. When N_(DBPS,Last) is an integer but

N_(DBPS, Last)/N_(ES)is not, the encoder may pad N_(DBPS,Last) bits before encoders at 302,and then unevenly distribute padding bits across encoders at 302. Forexample, as shown in the table in FIG. 3 , for a list of encoders 304,some encoders may have more bits (e.g., see 304 b) padded than the restencoders (e.g., see 304 a).

Specifically, the parameter N_(R) can be configured to be a differentvalue per coding scheme, e.g., for binary convolutional coding (BCC) andlow density parity-check (LDPC) coding. For example, the encoder can setN_(R)=1 for LDPC, and N_(R)=the number of bits per puncturing blockgiven the coding rate for BCC.

FIG. 4 provides an exemplary logic diagram illustrating an alternativeimplementation of an example special padding rule by adding additionalpadding bits, in accordance with various embodiments of the disclosure.Continuing on from 207 in FIG. 2 , the encoder may determine whether oneof N_(DBPS,Last) and

N_(DBPS, Last)/N_(ES)is not an integer at 401. If not, the encoder may proceed with 209.Otherwise, the encoder may pad additional bits to make both of the twoparameters integral, and then split the padding bits evenly acrossencoders at 402. For example, the encoder may first pad more bits ifN_(DBPS,Last) is not an integer, such that after padding the revisednumber of information bits for the last symbol may be determined basedon the following:

${{\overset{\sim}{N}}_{{DBPS},{Last}} = {\left\lceil {a \cdot \frac{1}{4} \cdot N_{SD} \cdot N_{SS} \cdot N_{BPSCS} \cdot R} \right\rceil.}},$wherein “┌ ┐” denotes a ceiling operation. Then the encoder may pad morebits if

N_(DBPS, Last)/N_(ES)is not an integer, such that after the padding the revised number ofinformation bits for the last symbol may be determined as follows:

${\overset{\sim}{\overset{\sim}{N}}}_{{DBPS},{Last}} = {\left\lceil \frac{{\overset{\sim}{N}}_{{DBPS},{Last}}}{N_{ES} \cdot N_{R}} \right\rceil \cdot N_{ES} \cdot {N_{R}.}}$

In an alternative implementation, at 403, the encoder may pad additionalbits to make N_(DBPS,Last) an integer, and apply 402 to unequallydistribute the bits across encoders.

FIG. 5 provides an exemplary logic diagram illustrating an alternativeimplementation of an example special padding rule by apply dynamicpuncturing for each encoder, in accordance with various embodiments ofthe disclosure. Similarly, continuing on from 401, when one ofN_(DBPS,Last) and

N_(DBPS, Last)/N_(ES)is not an integer, the encoder may use dynamic puncturing for eachencoder at 405. At 406, for each encoder,

⌈N_(DBPS, Last)/N_(ES)⌉may be fed, wherein “┌ ┐” denotes a ceiling operation. At 407, for thelast puncture block of each encoder, a dynamic puncture pattern can bedesigned for the available BCC output. For example, any puncture patterncan be applied, such that the number of output bits can be setequivalent to N_(CBPS,Last). If N_(CBPS,Last) is not an integer, thenthe number of output bits can be set equivalent to ┌N_(CBPS,Last)┐,wherein “┌ ┐” denotes a ceiling operation.

In an alternative implementation, the encoder can enforce the data bitsof the short symbol N_(DBPS,Short) to be an integer. For example, an f() mapping can be defined as the following:N_(DBPS,Short)=f(N_(DBPS,Short) ^((u))) such that N_(DBPS,Short) ^((u))is an integer.

In one example, the encoder can set Ñ_(DBPS,Short)^((u))=┌N_(DBPS,Short) ^((u))┐ or └N_(DBPS,Short) ^((u))┘, wherein “┌ ┐”denotes a ceiling operation, and “└ ┘” denotes a floor operation; andthen the SE parameter a and the data bits of the last OFDM symbolN_(DBPS,Last) ^((u)) can be obtained as illustrated in FIGS. 3-5 .

In another alternative implementation, the encoder may configure acompatible number of scheduled data subcarriers N_(SD) ^((u)). Forexample, Instead of using exactly ¼ of scheduled data tones, using acompatible N_(SD) that leads to integer N_(CBPS,Short) andN_(DBPS,Short) for all the MCS's. In this way, the number of informationbits of the short symbol can be set asN_(DBPS,Short)=N_(SD,Short-compatible)·N_(SS)·N_(BPSCS), whereN_(SD,Short-compatible) denotes a number of scheduled data subcarriersthat is compatible for the short symbol. For example,N_(SD,Short-compatible) can be set (close to) the value of N_(SD) of thesame bandwidth (BW) in 1× symbols. Examples of compatible N_(SD) areshown in the following:

TABLE 1 Example Compatible N_(SD) N_(SD) N_(SD,Short-Compatible) 24 6 4812 102 24 234 48 468 114 or 120 980 234, 240 or 246

FIG. 6 provides an exemplary logic diagram illustrating an alternativeimplementation of an example special padding rule by enforcing aninteger number of coded bits per symbol for short OFDM symbols, inaccordance with various embodiments of the disclosure. Continuing onfrom 207 in FIG. 2 , at 411, the encoder may enforce the number of codedbits of a short symbol N_(CBPS,short) to be an integer number. Forexample, the encoder can set as

${N_{{CBPS},{Short}} = {\left\lceil {\frac{1}{4} \cdot N_{SD} \cdot N_{SS} \cdot N_{BPSCS}} \right\rceil{or}\left\lfloor {\frac{1}{4} \cdot N_{SD} \cdot N_{SS} \cdot N_{BPSCS}} \right\rfloor}},$wherein “┌ ┐” denotes a ceiling operation, and “└ ┘” denotes a flooroperation. Or in another example, the encoder may use a “compatible”N_(SD) as discussed above in connection with Table 1, which may make theN_(CBPS,short) an integer number. In this case, the number of scheduleddata subcarriers for the short symbol can be set as

${N_{{SD},{Short}} = {\left\lceil {\frac{1}{4} \cdot N_{SD}} \right\rceil{or}\left\lfloor {\frac{1}{4} \cdot N_{SD}} \right\rfloor}},$wherein “┌ ┐” denotes a ceiling operation, and “└ ┘” denotes a flooroperation, and the number of information bits of the short symbol can beset as N_(CBPS,Short)=N_(SD,Short)·N_(SS).

At 412, the encoder may determine the SE parameter a by using a numberof information bits of the short symbol

N_(DBPS, Short) = ⌊N_(CBPS, Short) ⋅ R⌋,wherein “└ ┘” denotes a floor operation and then add the pre-FEC paddingbits. Specifically, for BCC, the number of information bits of the shortsymbol may be determined as follows:

$N_{{DBPS},{Short}} = {\left\lfloor \frac{N_{{CBPS},{Short}} \cdot R}{N_{ES} \cdot N_{R}} \right\rfloor \cdot N_{ES} \cdot {N_{R}.}}$In this case, a ceiling operation “┌ ┐” can be used alternatively forboth BCC and LDPC.

At 413, for LDPC, the encoder may determine all the LDPC parameters,such as but not limited to parity-check matrix, block length, and/or thelike. If an extra symbol is needed per LDPC encoding rule, the encodermay update the related LDPC parameters, and also update the number ofcoded bits of the last symbol N_(CBPS,Last) and the number ofinformation bits of the last symbol N_(DBPS,Last). At 414, the encodermay compute the post-FEC padding bits to fill up the last data symbol,e.g., for post-FEC padding at 105 in FIG. 1 .

In one implementation, after applying various special padding rules asillustrated in FIGS. 3-6 , the number of coded bits for the last symbolcan be re-computed (e.g., see 208 in FIG. 2 ). Specifically, in case ofLDPC, the number of coded bits for the last symbol N_(CBPS,Last) isupdated and used together with the number of information bits for thelast symbol N_(DBPS,Last) to determine LDPC parameters. For example,N_(CBPS,Last) can be determined based on

$N_{{CBPS},{Last}} = \left\lceil \frac{N_{{DBPS},{Last}}}{R} \right\rceil$or

$N_{{CBPS},{Last}} = {\left\lceil \frac{\left\lceil \frac{N_{{DBPS},{Last}}}{R} \right\rceil}{R} \right\rceil.}$N_(BPSCS), where R denotes the coding rate, and “┌ ┐” denotes a ceilingoperation.

For both BCC and LDPC, after pre-FEC padding parameters is determined,N_(CBPS,Last) can be used be the number of output bits for datatransmission (e.g., at 135 in FIG. 1 ).

The various examples of special padding rules to configure codingparameters as illustrated in FIGS. 3-6 , can be employedinterchangeably, dynamically, or in a combinational manner. The specialpadding rules can also be applied to scenarios when space-time blockcodes (STBC) are used. For example, when STBC is employed, the number ofsymbols N_(SYM) is calculated differently, but the number of coded bitsfor the last symbol N_(CBPS,Last) or the number of information bits forthe last symbol N_(DBPS,Last) can be obtained in a similar manner asdescribed in FIGS. 3-6 .

While various embodiments of the present disclosure have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the disclosure. It should beunderstood that various alternatives to the embodiments of thedisclosure described herein may be employed in practicing thedisclosure. It is intended that the following claims define the scope ofthe disclosure and that methods and structures within the scope of theseclaims and their equivalents be covered thereby.

The foregoing is merely illustrative of the principles of thisdisclosure, and various modifications can be made without departing fromthe scope of the present disclosure. The above-described embodiments ofthe present disclosure are presented for purposes of illustration andnot of limitation, and the present disclosure is limited only by theclaims that follow.

What is claimed is:
 1. A method for forward error correction (FEC)padding, the method comprising: obtaining, at a transceiver, a pluralityof data symbols for transmission; determining a number of informationbits that are available for inclusion in a last symbol of the pluralityof data symbols; selecting a compatible number of scheduled datasubcarriers, the compatible number being a fraction of a number ofscheduled data subcarriers used for transmission in a single symbolperiod under a same bandwidth; calculating an integer number ofinformation bits for the last symbol based on the compatible number ofscheduled data subcarriers; adding a number of padding bits to thenumber of information bits that are available for transmission, whereinthe number of padding bits and the number of information bits sum to theinteger number of information bits; and encoding, for data transmission,the plurality of data symbols, the plurality of data symbols includingthe last data symbol having the integer number of information bits. 2.The method of claim 1, wherein the number of padding bits is added tothe number of information bits before forward error-corrective encoding.3. The method of claim 1, wherein the number of padding bits is a firstnumber of padding bits, the method further comprising: adding a secondnumber of padding bits to the last symbol after forward error-correctiveencoding.
 4. The method of claim 3, wherein the second number of paddingbits consists of bits with value ‘0’.
 5. The method of claim 1, whereinthe compatible number of scheduled data subcarriers is dependent on acoding rate used for transmission in the single symbol period under thesame bandwidth.
 6. A system for forward error correction (FEC) padding,the system comprising: an input data processing module to obtain aplurality of data symbols for transmission; a pre-encoding paddingmodule communicatively coupled to the input data processing module, thepre-encoding padding module being configured to: determine a number ofinformation bits that are available for inclusion in a last symbol ofthe plurality of data symbols; select a compatible number of scheduleddata subcarriers, the compatible number being a fraction of a number ofscheduled data subcarriers used for transmission in a single symbolperiod under a same bandwidth; calculate an integer number ofinformation bits for the last symbol based on the compatible number ofscheduled data subcarriers; add a number of padding bits to the numberof information bits that are available for transmission, wherein thenumber of padding bits and the number of information bits sum to theinteger number of information bits; and encode, for data transmission,the plurality of data symbols, the plurality of data symbols includingthe last data symbol having the integer number of information bits. 7.The system of claim 6, wherein the number of padding bits is added tothe number of information bits before forward error-corrective encoding.8. The system of claim 6, wherein the number of padding bits is a firstnumber of padding bits, and wherein the pre-encoding padding module isfurther configured to: add a second number of padding bits to the lastsymbol after forward error-corrective encoding.
 9. The system of claim8, wherein the second number of padding bits consists of bits with value‘0’.
 10. The system of claim 6, wherein the compatible number ofscheduled data subcarriers is dependent on a coding rate used fortransmission in the single symbol period under the same bandwidth.